[gcc r11-3476] powerpc, libcpp: Fix gcc build with clang on power8 [PR97163]

[Jakub Jelinek]

https://gcc.gnu.org/g:d00b1b023ecfc3ddc3fe952c0063dab7529d5f7a

commit r11-3476-gd00b1b023ecfc3ddc3fe952c0063dab7529d5f7a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Sat Sep 26 10:07:41 2020 +0200

    powerpc, libcpp: Fix gcc build with clang on power8 [PR97163]
    
    libcpp has two specialized altivec implementations of search_line_fast,
    one for power8+ and the other one otherwise.
    Both use __attribute__((altivec(vector))) and the GCC builtins rather than
    altivec.h and the APIs from there, which is fine, but should be restricted
    to when libcpp is built with GCC, so that it can be relied on.
    The second elif is
    and thus e.g. when built with clang it isn't picked, but the first one was
    just guarded with
    and so according to the bugreporter clang fails miserably on that.
    
    The following patch fixes that by adding the same GCC_VERSION requirement
    as the second version.  I don't know where the 4.5 in there comes from and
    the exact version doesn't matter that much, as long as it is above 4.2 that
    clang pretends to be and smaller or equal to 4.8 as the oldest gcc we
    support as bootstrap compiler ATM.
    Furthermore, the patch fixes the comment, the version it is talking about is
    not pre-GCC 5, but actually the GCC 5+ one.
    
    2020-09-26  Jakub Jelinek  <jakub@redhat.com>
    
            PR bootstrap/97163
            * lex.c (search_line_fast): Only use _ARCH_PWR8 Altivec version
            for GCC >= 4.5.

Diff:
---
 libcpp/lex.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libcpp/lex.c b/libcpp/lex.c
index 9aec9e0bd04..2fe77d162a2 100644
--- a/libcpp/lex.c
+++ b/libcpp/lex.c
@@ -531,11 +531,11 @@ init_vectorized_lexer (void)
   search_line_fast = impl;
 }
 
-#elif defined(_ARCH_PWR8) && defined(__ALTIVEC__)
+#elif (GCC_VERSION >= 4005) && defined(_ARCH_PWR8) && defined(__ALTIVEC__)
 
 /* A vection of the fast scanner using AltiVec vectorized byte compares
    and VSX unaligned loads (when VSX is available).  This is otherwise
-   the same as the pre-GCC 5 version.  */
+   the same as the AltiVec version.  */
 
 ATTRIBUTE_NO_SANITIZE_UNDEFINED
 static const uchar *